Magnetic Resonance Imaging Procedure for Pelvic Fracture Urethral Injuries and Recto Urethral Fistulas: a Simplified Protocol Pankaj M

Turk J Urol 2021; 47(1): 35-42 • DOI: 10.5152/tud.2020.20472 35 GENERAL UROLOGY Original Article

Magnetic resonance imaging procedure for pelvic fracture urethral injuries and recto urethral fistulas: A simplified protocol Pankaj M. Joshi , Devang J. Desai , Darshan Shah , Devashree P. Joshi , Sanjay B. Kulkarni

Cite this article as: Joshi PM, Desai DJ, Shah D, Joshi DP, Kulkarni SB. Magnetic resonance imaging procedure for pelvic fracture urethral injuries and recto urethral fistulas: A simplified protocol. Turk J Urol 2021; 47(1): 35-42.

ABSTRACT Objective: The urethral gap in pelvic fracture urethral injury (PFUI) is traditionally assessed using voiding cystourethrogram (VCUG) and retrograde urethrogram (RGU). Magnetic resonance imaging (MRI) is performed in complex cases. We assessed the refined “Joshi” MRI protocol to evaluate complex urethral defects after PFUI. Material and methods: A prospective study was conducted at our center from January 2018 to January 2020, involving patients aged >18 years with PFUI, suitable for MRI, and those who gave consent to perform standard RGU, VCUG, and MRI using standard and “Joshi” protocol. Forty men were included in the study. Distance between urethral/prostatic stumps was measured. Image quality was scored by four radiologists and four urologists. The surgical approach and type of PFUI repair were noted. We also established the need for inferior pubectomy by assessing the position of the posterior urethra (membranous) in relation to a horizontal line drawn from the lower edge of the pubic bone anteriorly to the rectum posteriorly in a sagittal image. Results: The mean age was 30 years (SD, 5.25; range, 21–43), and the time from injury to imaging was 4 months (3–10 months); 40% of the men underwent crural separation, 57.5%, inferior pubectomy, and 2.5%, crural rerouting. There was a difference of 0.3 to 1.1 cm in the urethral gap measurements between MR images using the standard versus “Joshi” technique. MRI identified complex injuries such as rectourethral fistula, the need for inferior pubectomy, and the orientation of the posterior urethra. Urologists’ and radiologists’ satisfaction scores for the MR images were satisfactory to excellent. If the posterior urethra was over the defined mark, there was a 100% likelihood of inferior pubectomy (23/40 patients). Conclusion: MR image acquisition using the “Joshi” protocol provided high-quality anatomical information in PFUI cases to assist with surgical planning. Keywords: MRI; pelvic fracture urethral injury; stricture urethra; trauma; urethroplasty.

Introduction Preoperative assessment of the urethral gap is important when deciding the type of surgical Pelvic fracture urethral injuries (PFUIs) occur approach. In most cases, a gap of less than Kulkarni Reconstructive in 5–25% cases of pelvic fractures.[1,2] Motor 2.5 cm can be treated by a simple perineal Urology Center, Pune, India vehicle collisions are the most common cause approach, while larger gaps may require an Submitted: of pelvic fractures. The incidence of urethral elaborate perineal approach or trans-pubic 19.10.2020 injuries as a result of motor vehicles varies procedure. [9-14] Therefore, preoperative gap Accepted: between 36% in India and 15% in Italy and assessment aids in determining the type of 16.11.2020 USA.[3] Pelvic fracture results in urethral approach. Conventionally, a retrograde ure- Corresponding Author: injury at the membranobulbar junction.[4-6] throgram (RGU) along with a voiding cysto- Pankaj M. Joshi urethrogram (VCUG) is performed, while in E-mail: As a result of disruption of the ligamentous [email protected] attachments of the urethra and injury to the complex cases, an MRI of the pelvis is per- periprostatic venous plexus, a hematoma is formed to assess the urethral gap and delineate ©Copyright 2021 by Turkish Association of Urology formed that displaces the prostate cephalad additional pathologies such as rectourethral and posteriorly.[7] In PFUI, there is no loss of fistula, orientation of the proximal urethral Available online at [8] www.turkishjournalofurology.com urethral tissue. end, presence of bone fragments, etc. Turk J Urol 2021; 47(1): 35-42 36 DOI 10.5152/tud.2020.20472

MR images in these cases can be difficult to assess by urolo- diluted contrast and normal saline, and the patient was asked to gists due to the non-standardization of image acquisition, and void;[15] at the same time, the voiding RGU was performed by not many urologists are well versed with MRI. Hence, most injecting the same solution via the urethra while applying penile urologists prefer using RGU and VCUG, missing out on crucial traction. A combined RGU and VCUG image was obtained. additional soft tissue information that can be obtained from a Thereafter, pelvic MRI procedures were performed using both pelvic MRI, especially in complex cases. the standard and “Joshi” protocol.

The aim of this study was to describe a simplified protocol for MRI protocol MRI in patients with PFUI and compare differences in the qual- Standard MR pelvis was performed on an empty bladder. MR ity and precision between the modalities. We hypothesized that images using the standard procedure and the “Joshi” proto- the protocol is feasible, the results are reproducible with similar col were obtained. The night before the assessment date, the image acquisition, and the images provide a good anatomical patient was premedicated with a selective alpha blocker so as outline for surgical planning. to open the bladder neck. The bladder was filled with saline using an SPC. A mixture of sterile saline and lignocaine jelly Material and methods was injected via the meatus, and the penis was clamped using a gauze piece. A T2 sagittal image was acquired on a full blad- The current study assessed a refined “Joshi” protocol for MR der with the patient attempting to pass urine. The images were image acquisition designed specifically for evaluation of complex used to evaluate the urethral gap, orientation of the posterior urethral defects after PFUI. The distance between the urethral urethra, and the relation of the posterior urethra to the rectum. ends was measured. Image quality was scored by four radiolo- A urethral gap assessment was done for each patient. The gists and four urologists. The surgical approach and type of PFUI surgical approach and type of PFUI repair were noted. Image repair were noted. We also established the need for inferior quality was scored by four radiologists and four urologists as pubectomy by assessing the position of the posterior urethra to excellent (4), satisfactory (3), disappointed (2) and extremely a horizontal line drawn from the lower edge of the pubic bone disappointed (1). anteriorly to the rectum posteriorly in a sagittal image. Statistical analysis Study design Continuous variables were assessed using a paired t-test. After obtaining approval from the ethics committee and IRB Nominal variables were assessed using the Chi-squared test. (KESI/05), we initiated this prospective study evaluating MRI The correlation between the modalities was calculated using imaging for PFUI. All male patients aged >18 years who pre- the paired t-test. SPSS software was used for statistical analy- sented with posterior urethral injury, suitable for MRI, and sis. agreed to participate in the study were included. Written and informed consent was taken. Patients with incomplete urethral Results disruption, those not suitable for MRI, and those who did not consent to participate in the study were excluded. Data on Patient population demographic information, health history, injury characteristics, Between January 2018 and January 2020, 297 patients pre- imaging studies, and type of surgical repair were collected. sented with PFUI; 40 male patients were eligible and agreed to participate in the study. The mean age was 30 years (SD, 5.25; VCUG and RUG protocol range, 21–43 years) and the time from injury to imaging was All patients underwent RGU and VCUG. The bladder was filled 4 months (3–10 months); 40% of the men underwent step 2 using gravity filling via a suprapubic catheter (SPC), with 50% (corporal separation), while 57.5% underwent step 3 (inferior pubectomy), and 2.5% underwent step 4 (crural rerouting) pro- Main Points: cedures. • MRI in patients with pelvic fracture urethral injuries and rectourethral fistulas should be performed using the Joshi protocol: Results of VCUG/RUG full bladder and lignocaine jelly in anterior urethra; T2 sagittal VCUG and RGU were performed on all patients. The average images. gap was 2.77 cm (SD, 0.53; range, 1–4 cm). • The Joshi protocol can help predict the need for pubectomy. Results of traditional MRI • This protocol helps determine the direction of displacement of the prostate and posterior urethra in cases of PFUI. Traditional MRI was performed on an empty bladder. The urethral gap ranged from 1 to 5 cm. The average gap assessment • This protocol can provide high-quality MR images. was 3.27 cm (SD, 0.68). Joshi et al. MRI for PFUI 37

Results of “Joshi” protocol 25 MRI with the “Joshi” protocol was performed with a full bladder, premedication with alpha blocker, and instillation of saline 20 with gel in the urethra. The urethral gap ranged from 1 to 4 cm. The average gap was 2.65 cm (SD, 0.53). The urethral gap range 15 on the “Joshi” MR image was lower than that on standard MR image. 10

5 Comparison between the modalities The urethral gap differed between the standard MRI and “Joshi” 0 protocol MRI (range, 0.3–1.1 cm) (Table 1). The correlation Step 2 Step 3 Step 4 coefficient between the standard MRI, RGU, and VCUG was Below Above 0.897 while between the “Joshi” protocol MRI, RGU, and VCUG, it was 0.96 on the paired t-test. The results of the MRI Figure 1. Need for pubectomy based on the horizontal line performed using “Joshi” protocol were very close to the results drawn between inferior pubic margin and rectum of conventional RGU and VCUG. The participating urologists stated that MR images acquired using our protocol essentially mirrored the images obtained from conventional RGU and VCUG and were easy to interpret, while providing additional information on anatomical and soft tissue.

Quality assessment of images between evaluators The satisfaction scores of both radiologists and urologists ranged from satisfactory to excellent. The average scores of the radiologists and urologists were 3.8 and 3.82, with the median score being 4 for both.

Need for inferior pubectomy Our protocol was also used to determine the need for inferior pubectomy in the patients (gap close to 3 cm) by assessing the position of the urethral stump to a horizontal line drawn from the lower edge of the pubic bone anteriorly to the rectum posteriorly in a sagittal image. The majority of the patients in our study required inferior pubectomy (23/40 patients). The risk of inferior pubectomy was 100% if the urethral stump was over the defined line, being statistically significant for Step 2 vs. Step 3 (p<0.0001) and Step 2 vs. step 4 (p<0.0001) (Figure 1). Figure 2. Routine magnetic resonance imaging (MRI) at the radiology department Discussion protocol, the edges of the urethra were well defined due to the Assessment of the urethral gap in PFUI is of relevance in decid- saline that acts as a natural contrast on MRI (Figures 2-5). ing the approach to anastomotic urethroplasty. Conventional [16] assessments include RGU and VCUG. However, the accuracy In a study by Dixon et al. involving 18 patients, a T2-weighted of these assessments is limited when the urethral gap of the MR image was acquired to evaluate PFUI patients. In our pro- bladder neck is not open, there is prostatic displacement on the tocol, we used similar image acquisition modalities but with horizontal or vertical axis, and when the condition is compli- additional steps of a full bladder, pre-MRI alpha blocker admin- cated, e.g., fistula, diverticula, or false passages. MRI has been istration, and urethral instillation of a premixed solution of ster- used in complex PFUI cases to overcome these limitations.[16] ile saline and jelly in the urethra. This assists in clearly defining the ends of the urethra and gap assessment. On comparing the protocols, we found that the posterior and anterior urethral outlines were not well defined, and hence, Another study by Oh et al.[17] involving 25 patients with PFUI the urethral gap assessment was difficult. While, in the “Joshi” compared MRI with conventional RGU and VCUG and con- Turk J Urol 2021; 47(1): 35-42 38 DOI 10.5152/tud.2020.20472

Table 1. Study results Position of posterior urethra in relation to the line from lower Patient MRI - MRI - “Joshi RGU + edge of pubic bone Surgical Radiologist Urologist number Age standard protocol” Difference VCUG to rectum approach assessment assessment 1 28 4 3.2 0.8 3.1 Above Step 3 4 4 2 32 3.5 2.7 0.8 2.7 Above Step 3 3 4 3 43 3 2.4 0.6 2.4 Below Step 2 3 4 4 21 4 3.3 0.7 3.2 Above Step 3 4 4 5 31 5 4 1 4 Above Step 4 4 4 6 27 4 3 1 2.8 Above Step 3 4 4 7 26 3.5 2.4 1.1 3 Above Step 3 4 4 8 33 3 2.6 0.4 2.8 Above Step 3 3 3 9 34 2.8 2.1 0.7 2 Below Step 2 4 4 10 37 3 2.7 0.3 2.8 Above Step 3 3 3 11 29 2.5 2.2 0.3 2.4 Below Step 2 3 3 12 33 3 2 1 2.4 Below Step 2 4 4 13 32 2.7 2.4 0.3 2.6 Above Step 3 4 3 14 28 2.6 2.1 0.4 2.2 Below Step 2 3 3 15 21 3.5 3 0.5 3.1 Above Step 3 4 4 16 29 2.8 2.4 0.4 2.6 Below Step 2 4 4 17 41 4 3 1 3.3 Above Step 3 4 4 18 28 3 2.7 0.3 2.9 Above Step 3 3 4 19 21 4 2.9 1.1 3 Above Step 3 4 4 20 26 3 2.7 0.3 3 Above Step 3 4 4 21 27 2 1.8 0.2 2 Below Step 2 3 3 22 32 3.2 2.8 0.4 2.9 Above Step 3 4 4 23 35 3.7 2.8 0.9 2.9 Above Step 3 4 3 24 34 3 2.7 0.3 2.9 Below Step 2 4 4 25 26 3.7 3 0.7 3.1 Above Step 3 4 4 26 37 2.9 2.6 0.3 2.6 Below Step 2 4 4 27 26 2.8 2.1 0.7 2 Below Step 2 4 4 28 23 3.6 2.6 1 2.8 Below Step 2 4 4 29 37 1.3 1 0.3 1 Below Step 2 4 4 30 27 3.3 2.8 0.5 2.7 Below Step 2 4 4 31 34 3.4 2.9 0.5 3 Above Step 3 4 4 32 32 3.2 2.6 0.6 2.8 Above Step 3 4 4 33 30 3.7 2.9 0.8 3 Below Step 2 4 4 34 28 2.9 2.3 0.6 2.5 Below Step 2 4 4 35 26 4 3.1 0.9 3 Above Step 3 4 4 36 23 3.7 3.2 0.4 3.3 Above Step 3 4 4 37 24 2 1.6 0.4 1.7 Below Step 2 4 4 38 34 4.1 3.3 0.8 3.4 Above Step 3 4 4 39 33 3.7 2.7 1 2.8 Above Step 3 4 4 40 32 3.8 3.3 0.5 3.4 Above Step 3 4 4 Joshi et al. MRI for PFUI 39

Figure 3. Magnetic resonance imaging (MRI) in same patient with full bladder using Joshi protocol Figure 5. Magnetic resonance imaging (MRI) showing high- lying prostate with posterior dislocation

Figure 6. Horizontal line drawn from lower edge of pubic bone can predict the need for pubectomy

Can we predict the need for pubectomy? A horizontal line was drawn from the lower edge of the pubic bone anteriorly to the rectum posteriorly in the sagittal image. If the tip of the posterior urethra (membranous urethra) was seen Figure 4. Magnetic resonance imaging (MRI) with empty below this horizontal line, the risk of inferior pubectomy was bladder low, but if the tip was above this horizontal line, and the risk was high (Figure 6). A high-lying posterior urethra would indicate cluded that MRI was more accurate than conventional imaging the need for a transpubic approach. The majority of the patients modalities. Our study compared RGU, VCUG, standard MRI, in our study required inferior pubectomy (23/40 patients). The and “Joshi” MRI protocol. The main advantage of the Joshi increased need for inferior pubectomy in India has been previ- protocol is that it uses saline as a natural contrast and delineates ously published.[14] Joshi et al.[18] described the technique of 3D anatomical structures to improve image acquisition during an printing in complex cases, which also serves a similar purpose as MRI study. 3D visualization, which assists in preoperative planning. Turk J Urol 2021; 47(1): 35-42 40 DOI 10.5152/tud.2020.20472

a b

Figure 7. a-d. (a) Two-dimensional voiding cystourethrogram (VCUG) image. (b) Voiding cystourethrogram (VCUG) shows cur- ved posterior urethra but does not predict the direction of displacement. (c) Magnetic resonance imaging (MRI) with our protocol showing posterior displacement of prostate. (d) Three-dimensional magnetic resonance imaging (MRI) showing that the posterior urethra is displaced anteriorly

Orientation of the posterior urethra tum. A typical VCUG provides a 2D image (Figures 7a, b). Our The most feared complication of posterior urethroplasty is the MR protocol accurately assessed the displacement of posterior risk of rectal injury. The risk of rectal injury is higher if the urethra, towards the rectum or away from rectum, and assisted posterior urethra is placed high and displaced towards the rec- in surgical technique (Figures 7c, d). In cases of rectourethral Joshi et al. MRI for PFUI 41

Figure 9. Algorithim for imaging in pelvic fracture urethral injuries

Conclusion

MR image acquisition using the simplified “Joshi” protocol gave good anatomical information in PFUI cases to assist with surgical planning. The images were well scored by both radiologists and urologists. Our MRI protocol may be used to replace conventional RGU and VCUG in cases of complex PFUI.

Ethics Committee Approval: Ethics committee approval was received for this study from the ethics committee of Kulkarni Endosurgery and Reconstructive Urology Centre IRB (KESI/05).

Informed Consent: Written informed consent was obtained from patients who participated in this study.

Peer-review: Externally peer-reviewed.

Author Contributions: Concept – P.M.J., D.J.D., S.B.K.; Design – P.M.J., D.J.D., S.B.K.; Supervision – P.M.J., D.J.D.; Resources – D.S., D.P.J.; Materials – P.M.J., D.J.D.; Data Collection and/or Processing – P.M.J., D.J.D.; Analysis and/or Interpretation – P.M.J., D.J.D., D.S., D.P.J.; Literature Search – D.J.D., P.M.J.; Writing Manuscript – D.J.D., P.M.J.; Critical Review – P.M.J., D.J.D., S.B.K.; Other – D.S., D.P.J.

Figure 8. Magnetic resonance imaging (MRI) with our techni- Conflict of Interest: The authors have no conflicts of interest to declare. que in patients with rectourethral fistula Financial Disclosure: The authors declared that this study has received no financial support. fistula, by injecting lignocaine jelly in the anterior urethra, we could accurately demonstrate the fistulous tract (Figure 8). We References propose a algorithm for imaging in pelvic fracture urethral inju- 1. Gómez RG, Mundy T, Dubey D, El-Kassaby AW, Firdaoessaleh, ries (Figure 9). Kodama R. SIU/ICUD consultation on urethral strictures: pelvic Turk J Urol 2021; 47(1): 35-42 42 DOI 10.5152/tud.2020.20472

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